<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

</head>
<body>
<script>
    // ES5写法 ：var 变量名称=值
    var name = '张三';
    // 浏览器控制台输出信息
    console.log(name)
    // ES6+写法：let 变量名称=值
    let age = 18;
    console.log("age修改前：",age)
    age = 20
    console.log("age修改后：",age)
    // ES6+写法：const 常量名称=值
    const height = 1.88;
    console.log(height)
    // height = 1.9 // 修改常量会报错
    // console.log(height)
</script>
</body>
</html>
